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Infection transmitted through human sexual behavior From Wikipedia, the free encyclopedia
A sexually transmitted infection (STI), also referred to as a sexually transmitted disease (STD) and the older term venereal disease (VD), is an infection that is spread by sexual activity, especially vaginal intercourse, anal sex, oral sex, or sometimes manual sex.[1][5][6] STIs often do not initially cause symptoms,[1] which results in a risk of transmitting them on to others.[7][8] The term sexually transmitted infection is generally preferred over sexually transmitted disease or venereal disease, as it includes cases with no symptomatic disease.[9] Symptoms and signs of STIs may include vaginal discharge, penile discharge, ulcers on or around the genitals, and pelvic pain.[1] Some STIs can cause infertility.[1]
Sexually transmitted infection | |
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Other names | Sexually transmitted disease (STD); Venereal disease (VD) |
Condom Museum, Bangkok | |
Specialty | Infectious disease |
Symptoms | None, vaginal discharge, penile discharge, ulcers on or around the genitals, pelvic pain[1] |
Complications | Infertility[1] |
Causes | Infections commonly spread by sex[1] |
Prevention | Sexual abstinence, vaccinations, condoms[2] |
Frequency | 1.1 billion (STIs other than HIV/AIDS, 2015)[3] |
Deaths | 108,000 (STIs other than HIV/AIDS, 2015)[4] |
Bacterial STIs include chlamydia, gonorrhea, and syphilis.[1] Viral STIs include genital warts, genital herpes, and HIV/AIDS.[1] Parasitic STIs include trichomoniasis.[1] Most STIs are treatable and curable, of the most common infections; syphilis, gonorrhea, chlamydia, and trichomoniasis are curable, while HIV/AIDS and genital herpes are not curable.[1] Some vaccinations may decrease the risk of certain infections including hepatitis B and few types of HPV.[2] Safe sex practices such as use of condoms, having smaller number of sexual partners, and being in a relationship in which each person only has sex with the other also decreases STIs risk.[1][2] Comprehensive sex education may also be useful.[10]
STI diagnostic tests are usually easily available in the developed world, but they are often unavailable in the developing world.[1] There is often shame and stigma associated with STIs.[1] In 2015, STIs other than HIV resulted in 108,000 deaths worldwide.[4] Globally, in 2015, about 1.1 billion people had STIs other than HIV/AIDS.[3] About 500 million have either syphilis, gonorrhea, chlamydia or trichomoniasis.[1] At least an additional 530 million have genital herpes, and 290 million women have human papillomavirus.[1] Historical documentation of STIs in antiquity dates back to at least the Ebers Papyrus (c. 1550 BCE) and the Hebrew Bible/Old Testament (8th/7th C. BCE).[11]
Not all STIs are symptomatic, and symptoms may not appear immediately after infection. In some instances a disease can be carried with no symptoms, which leaves a greater risk of passing the disease on to others. Depending on the disease, some untreated STIs can lead to infertility, chronic pain or death.[12]
The presence of an STI in prepubescent children may indicate sexual abuse.[13]
A sexually transmitted infection present in a pregnant woman may be passed on to the infant before or after birth.[14]
Risk of transmission per unprotected sexual act with an infected person[15][16][17][18][19][20][21][22][23][24][25][26][27] | |||
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Known risks | Possible | ||
Performing oral sex on a man |
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Performing oral sex on a woman | |||
Receiving oral sex—man | |||
Receiving oral sex—woman | |||
Vaginal sex—man | |||
Vaginal sex—woman | |||
Anal sex—insertive | |||
Anal sex—receptive | |||
Anilingus |
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Sexually transmitted infections include:
Twenty-seven different viruses have been identified in semen. Information on whether or not transmission occurs or whether the viruses cause disease is uncertain. Some of these microbes are known to be sexually transmitted.[76]
Many STIs are (more easily) transmitted through the mucous membranes of the penis, vulva, rectum, urinary tract and (less often—depending on type of infection) the mouth, throat, respiratory tract and eyes.[77] The visible membrane covering the head of the penis is a mucous membrane, though it produces no mucus (similar to the lips of the mouth). Mucous membranes differ from skin in that they allow certain pathogens into the body. The amount of contact with infective sources which causes infection varies with each pathogen but in all cases, a disease may result from even light contact from fluid carriers like venereal fluids onto a mucous membrane.[citation needed]
Some STIs such as HIV can be transmitted from mother to child either during pregnancy or breastfeeding.[78][79] Healthcare professionals suggest safer sex, such as the use of condoms, as a reliable way of decreasing the risk of contracting sexually transmitted infections during sexual activity, but safer sex cannot be considered to provide complete protection from an STI. The transfer of and exposure to bodily fluids, such as blood transfusions and other blood products, sharing injection needles, needle-stick injuries (when medical staff are inadvertently jabbed or pricked with needles during medical procedures), sharing tattoo needles, and childbirth are other avenues of transmission. These different means put certain groups, such as medical workers, and haemophiliacs and drug users, particularly at risk.[citation needed]
It is possible to be an asymptomatic carrier of sexually transmitted infections. In particular, sexually transmitted infections in women often cause the serious condition of pelvic inflammatory disease.[80]
Testing may be for a single infection, or consist of a number of tests for a range of STIs, including tests for syphilis, trichomonas, gonorrhea, chlamydia, herpes, hepatitis, and HIV. No procedure tests for all infectious agents.
STI tests may be used for a number of reasons:
Early identification and treatment results in less chance to spread disease, and for some conditions may improve the outcomes of treatment. There is often a window period after initial infection during which an STI test will be negative. During this period, the infection may be transmissible. The duration of this period varies depending on the infection and the test. Diagnosis may also be delayed by reluctance of the infected person to seek a medical professional. One report indicated that people turn to the Internet rather than to a medical professional for information on STIs to a higher degree than for other sexual problems.[81]
Until the 1990s,[citation needed] STIs were commonly known as venereal diseases, an antiquated euphemism derived from the Latin venereus, being the adjectival form of Venus, the Roman goddess of love.[82] However, in the post-classical education era the euphemistic effect was entirely lost, and the common abbreviation "VD" held only negative connotations. Other former euphemisms for STIs include "blood diseases" and "social diseases".[83] The present euphemism is in the use of the initials "STI" rather than in the words they represent. The World Health Organization (WHO) has recommended the more inclusive term sexually transmitted infection since 1999.[9] Public health officials originally introduced the term sexually transmitted infection, which clinicians are increasingly using alongside the term sexually transmitted disease in order to distinguish it from the former.[citation needed]
Strategies for reducing STI risk include: vaccination, mutual monogamy, reducing the number of sexual partners, and abstinence.[84] Also potentially helpful is behavioral counseling for sexually active adolescents and for adults who are at increased risk.[85] Such interactive counseling, which can be resource-intensive, is directed at a person's risk, the situations in which risk occurs, and the use of personalized goal-setting strategies.[86]
The most effective way to prevent sexual transmission of STIs is to avoid contact of body parts or fluids which can lead to transfer with an infected partner. Not all sexual activities involve contact: cybersex, phone sex or masturbation from a distance are methods of avoiding contact. Proper use of condoms reduces contact and risk. Although a condom is effective in limiting exposure, some disease transmission may occur even with a condom.[87]
Both partners can get tested for STIs before initiating sexual contact, or before resuming contact if a partner engaged in contact with someone else. Many infections are not detectable immediately after exposure, so enough time must be allowed between possible exposures and testing for the tests to be accurate. Certain STIs, particularly certain persistent viruses like HPV, may be impossible to detect.[medical citation needed]
Some treatment facilities use in-home test kits and have the person return the test for follow-up. Other facilities strongly encourage that those previously infected return to ensure that the infection has been eliminated. Novel strategies to foster re-testing have been the use of text messaging and email as reminders. These types of reminders are now used in addition to phone calls and letters.[88] After obtaining a sexual history, a healthcare provider can encourage risk reduction by providing prevention counseling. Prevention counseling is most effective if provided in a nonjudgmental and empathetic manner appropriate to the person's culture, language, gender, sexual orientation, age, and developmental level. Prevention counseling for STIs is usually offered to all sexually active adolescents and to all adults who have received a diagnosis, have had an STI in the past year, or have multiple sex partners.[86]
Vaccines are available that protect against some viral STIs, such as hepatitis A, hepatitis B, and some types of HPV.[89] Vaccination before initiation of sexual contact is advised to assure maximal protection. The development of vaccines to protect against gonorrhea is ongoing.[90]
Condoms and female condoms only provide protection when used properly as a barrier, and only to and from the area that they cover. Uncovered areas are still susceptible to many STIs.[citation needed]
In the case of HIV, sexual transmission routes almost always involve the penis, as HIV cannot spread through unbroken skin; therefore, properly shielding the penis with a properly worn condom from the vagina or anus effectively stops HIV transmission. An infected fluid to broken skin borne direct transmission of HIV would not be considered "sexually transmitted", but can still theoretically occur during sexual contact. This can be avoided simply by not engaging in sexual contact when presenting open, bleeding wounds.[citation needed]
Other STIs, even viral infections, can be prevented with the use of latex, polyurethane or polyisoprene condoms as a barrier. Some microorganisms and viruses are small enough to pass through the pores in natural skin condoms but are still too large to pass through latex or synthetic condoms.[citation needed]
Proper male condom usage entails:[citation needed]
In order to best protect oneself and the partner from STIs, the old condom and its contents are to be treated as infectious and properly disposed of. A new condom is used for each act of intercourse, as multiple usages increase the chance of breakage, defeating the effectiveness as a barrier.[citation needed]
In the case of female condoms, the device consists of two rings, one in each terminal portion. The larger ring should fit snugly over the cervix and the smaller ring remains outside the vagina, covering the vulva. This system provides some protection of the external genitalia.[91]
The cap was developed after the cervical diaphragm. Both cover the cervix and the main difference between the diaphragm and the cap is that the latter must be used only once, using a new one in each sexual act. The diaphragm, however, can be used more than once. These two devices partially protect against STIs (they do not protect against HIV).[92]
Researchers had hoped that nonoxynol-9, a vaginal microbicide would help decrease STI risk. Trials, however, have found it ineffective[93] and it may put women at a higher risk of HIV infection.[94] There is evidence that vaginal dapivirine probably reduces HIV in women who have sex with men, other types of vaginal microbicides have not demonstrated effectiveness for HIV or STIs.[95]
There is little evidence that school-based interventions such as sexual and reproductive health education programmes on contraceptive choices and condoms are effective on improving the sexual and reproductive health of adolescents. Incentive-based programmes may reduce adolescent pregnancy but more data is needed to confirm this.[96]
Specific age groups, persons who participate in risky sexual behavior, or those have certain health conditions may require screening. The CDC recommends that sexually active women under the age of 25 and those over 25 at risk should be screened for chlamydia and gonorrhea yearly. Appropriate times for screening are during regular pelvic examinations and preconception evaluations.[97] Nucleic acid amplification tests are the recommended method of diagnosis for gonorrhea and chlamydia.[98] This can be done on either urine in both men and women, vaginal or cervical swabs in women, or urethral swabs in men.[98] Screening can be performed:
In the case of rape, the person can be treated prophylacticly with antibiotics.[99]
An option for treating partners of patients (index cases) diagnosed with chlamydia or gonorrhea is patient-delivered partner therapy, which is the clinical practice of treating the sex partners of index cases by providing prescriptions or medications to the patient to take to their partner without the health care provider first examining the partner.[100][needs update] In term of preventing reinfection in sexually transmitted infection, treatment with both patient and the sexual partner of patient resulted in more successful than treatment of the patient without the sexual partner. There is no difference in reinfection prevention whether the sexual partner treated with medication without medical examination or after notification by patient.[101]
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In 2008, it was estimated that 500 million people were infected with either syphilis, gonorrhea, chlamydia or trichomoniasis.[1] At least an additional 530 million people have genital herpes and 290 million women have human papillomavirus (HPV).[1] STIs other than HIV resulted in 142,000 deaths in 2013.[103] In the United States there were 19 million new cases of sexually transmitted infections in 2010.[104]
In 2010, 19 million new cases of sexually transmitted infections occurred in women in the United States.[5] A 2008 CDC study found that 25–40% of U.S. teenage girls has a sexually transmitted infection.[105][106] Out of a population of almost 295,270,000 people[107] there were 110 million new and existing cases of eight sexually transmitted infections.[108]
Over 400,000 sexually transmitted infections were reported in England in 2017, about the same as in 2016, but there were more than 20% increases in confirmed cases of gonorrhoea and syphilis. Since 2008 syphilis cases have risen by 148%, from 2,874 to 7,137, mostly among men who have sex with men. The number of first cases of genital warts in 2017 among girls aged 15–17 years was just 441, 90% less than in 2009 – attributed to the national HPV immunisation programme.[109]
AIDS is among the leading causes of death in present-day Sub-Saharan Africa.[110] HIV/AIDS is transmitted primarily via unprotected sexual intercourse. More than 1.1 million persons are living with HIV/AIDS in the United States,[111] and it disproportionately impacts African Americans.[112] Hepatitis B is also considered a sexually transmitted infection because it can be spread through sexual contact.[113] The highest rates are found in Asia and Africa and lower rates are in the Americas and Europe.[114] Approximately two billion people worldwide have been infected with the hepatitis B virus.[115]
The first well-recorded European outbreak of what is now known as syphilis occurred in 1494 when it broke out among French troops besieging Naples in the Italian War of 1494–98.[116] The disease may have originated from the Columbian Exchange.[117][118] From Naples, the disease swept across Europe, killing more than five million people.[119] As Jared Diamond describes it, "[W]hen syphilis was first definitely recorded in Europe in 1495, its pustules often covered the body from the head to the knees, caused flesh to fall from people's faces, and led to death within a few months," rendering it far more fatal than it is today. Diamond concludes, "[B]y 1546, the disease had evolved into the disease with the symptoms so well known to us today."[120] Gonorrhea is recorded at least up to 700 years ago and associated with a district in Paris formerly known as "Le Clapiers". This is where the prostitutes were to be found at that time.[90]
Prior to the invention of modern medicines, sexually transmitted infections were generally incurable, and treatment was limited to treating the symptoms of the infection. The first voluntary hospital for STIs was founded in 1746 at London Lock Hospital.[121] Treatment was not always voluntary: in the second half of the 19th century, the Contagious Diseases Acts were used to arrest suspected prostitutes. In 1924, a number of states concluded the Brussels Agreement, whereby states agreed to provide free or low-cost medical treatment at ports for merchant seamen with STIs. A proponent of these approaches was Nora Wattie, OBE, Venereal Diseases Officer in Glasgow from 1929, encouraged contact tracing and volunteering for treatment, rather than the prevailing more judgemental view and published her own research on improving sex education and maternity care.[122]
The first effective treatment for a sexually transmitted infection was salvarsan, a treatment for syphilis. With the discovery of antibiotics, a large number of sexually transmitted infections became easily curable, and this, combined with effective public health campaigns against STIs, led to a public perception during the 1960s and 1970s that they have ceased to be a serious medical threat.[citation needed]
During this period, the importance of contact tracing in treating STIs was recognized. By tracing the sexual partners of infected individuals, testing them for infection, treating the infected and tracing their contacts, in turn, STI clinics could effectively suppress infections in the general population.[citation needed]
In the 1980s, first genital herpes and then AIDS emerged into the public consciousness as sexually transmitted infections that could not be cured by modern medicine. AIDS, in particular, has a long asymptomatic period—during which time HIV (the human immunodeficiency virus, which causes AIDS) can replicate and the disease can be transmitted to others—followed by a symptomatic period, which leads rapidly to death unless treated. HIV/AIDS entered the United States from Haiti in about 1969.[123] Recognition that AIDS threatened a global pandemic led to public information campaigns and the development of treatments that allow AIDS to be managed by suppressing the replication of HIV for as long as possible. Contact tracing continues to be an important measure, even when diseases are incurable, as it helps to contain infection.
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